Pd-M-TiO_(2)(M=Mn,Cu,Ce and Fe)as passive NO_(x) adsorber(PNA)at low temperature  

Pd-M-TiO_(2)(M=Mn,Cu,Ce and Fe)催化剂的低温氮氧化物吸附性能

作　　者：WANG Yi-nan ZHAO Xu-teng ZHENG Zu-wei JIANG Han CHEN Ting ZHANG Yi-ran CAO Hong-lin LIN He ZHAN Reggie 王一男;赵旭腾;郑祖伟;蒋涵;陈婷;张毅然;曹宏林;林赫;湛日景(Key Laboratory for Power Machinery and Engineering of Ministry of Education,Shanghai Jiao Tong University,Shanghai 200240,China;Beijing Vehicle Emissions Management Center,Beijing 100081,China)

机构地区：[1]Key Laboratory for Power Machinery and Engineering of Ministry of Education,Shanghai Jiao Tong University,Shanghai 200240,China [2]Beijing Vehicle Emissions Management Center,Beijing 100081,China

出　　处：《Journal of Central South University》2022年第7期2253-2265,共13页中南大学学报（英文版）

基　　金：Project(52106173)supported by the National Natural Science Foundation of China;Project(2020TQ0187)supported by the Postdoctoral Research Foundation of China。

摘　　要：A series of transition metal Mn,Cu,Ce and Fe were loaded on TiO_(2) by sol-gel method with noble metal Pd as promotor for the application of passive NO_(x) absorber.Experiments on adsorption and desorption of NO_(x) were conducted and characterization methods such as X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM)and in situ Fourier transform infrared spectroscopy(in situ DRIFTS)were involved.The experimental results show that Mn-contained catalysts,Mn-Ti and Pd-Mn-Ti,performed excellent NO_(x) adsorbing ability and appropriate desorption temperature window.On the other hand,Ce-and Cu-contained samples were not suitable for the purpose of PNA.In addition to the low adsorption capacity,these two series of catalysts released massive amount of NO below 150℃.Characterization results indicated that Pd was highly dispersed on all catalysts.The loading of Pd lowered not only the valence states of transition metals but surface oxygen percentage as well.From in situ DRIFTS tests,the Pd had little influence on the types of adsorbed substances for Mn,Ce and Cu series.However,the storage forms of NO_(x) were obviously different on Pd-Fe-Ti and Fe-Ti.本文采用溶胶-凝胶法制备了以TiO_(2)为载体,Mn、Cu、Ce、Fe为主要活性成分,贵金属Pd为促进组分的一系列催化剂,并将其用于氮氧化物的吸附(PNA)。采用XRD、XPS、TEM以及原位DRIFTS等手段对催化剂进行表征。NO_(x)吸脱附试验结果表明,含Mn催化剂(Pd-Mn-Ti以及Mn-Ti)有较强的NO_(x)吸附能力且具有合适的脱附温度窗口。而含Ce、Cu催化剂不适合作低温NO_(x)吸附催化剂,NO_(x)的吸附量较低,且在随后的程序升温脱附试验中,低于150℃即有大量NO脱附,不利于在下游SCR催化剂进行进一步反应。XRD和TEM结果表明,贵金属Pd在催化剂表面分散较好。XPS结果显示,负载Pd以后Mn、Cu、Ce、Fe这四种金属的价态都有降低,并同时都伴随有表面氧浓度降低。由此可见,元素价态和表面氧浓度并非是影响NO_(x)吸附性能的主要因素。从原位DRIFTS结果可以看出,Pd对于氮氧化物在含Mn、Cu、Ce催化剂表面吸附形式的影响较小,但对于NO_(x)在含Fe催化剂上的吸附形式和吸附量都有着显著影响,可推测Pd-Fe之间有着较强的相互作用。

关 键 词：passive NO_(x)adsorber low temperature absorption manganese Pd-Fe interaction 

分 类 号：X701[环境科学与工程—环境工程] TQ426[化学工程]